The Lord Lieutenant of County Down is permitted to appoint a Vice Lord Lieutenant and up to 30 Deputy Lieutenants. The number of Deputy Lieutenants in each County is proportional to the population.The Deputy Lieutenants assist the Lord Lieutenant in the various tasks that he needs to perform. The Queen has to approve of the appointment of the Vice Lord Lieutenant & is only required to "Not Disapprove" of the appointment of the Deputy Lieutenants.
Deputy Lieutenants carry the suffix "DL" after their name. They normally retire, like the Lord Lieutenant, on their 75th birthday but they are permitted to keep the suffix for the rest of their life.
The Lord Lieutenant is also permitted to appoint a "Clerk". The amount of work that the clerk does varies enormously from county to county depending upon how busy the Lord Lieutenant is and how much of the administration of the Lieutenancy the Lord Lieutenant is able to perform himself. In County Down the Clerk is Michael Watt and he is also a Deputy Lieutenant. In Northern Ireland, the Lord Lieutenants are all assisted by the Northern Ireland Office and this does substantially reduce some of the administrative work required.
Deputy Lieutenants are the "Eyes & Ears" of the Lieutenancy. They can both actively report on items of interest to the Lord Lieutenant and also investigate people and organisations on behalf of the Lord Lieutenant. These may be, amongst many other things, people celebrating a 100th birthday, a candidate for a possible honour or a voluntary organisation that is a possible candidate for the Queen's Award for Voluntary Service.